Cellular communications systems continue to grow in popularity and have become an integral part of both personal and business communications. Cellular telephones allow users to place and receive voice calls most anywhere they travel. Moreover, as cellular telephone technology has increased, so too has the functionality of cellular devices and the different types of devices available to users. For example, many cellular devices now incorporate personal digital assistant (PDA) features such as calendars, address books, task lists, etc. Moreover, such multi-function devices may also allow users to wirelessly send and receive electronic mail (email) messages and access the Internet via a cellular network and/or a wireless local area network (WLAN), for example. Cameras have also been incorporated in cellular phones.
Even so, as the functionality of cellular communications devices continues to increase, so too does the demand for smaller devices which are easier and more convenient for users to carry. One challenge this poses for cellular device manufacturers is how to include all of the necessary components to provide desired functionality within a relatively small form factor.
In addition to meeting desired consumer demands, other constraints may also be placed on mobile device manufacturers that may require additional components to be included within a device. For example, in the U.S., pursuant to the Hearing Aid Compatibility (HAC) Act of 1988, the FCC requires cell phone makers to produce several models of devices that are designed to be compatible with hearing aids. FCC rules require that phones subject to the HAC Act: (1) produce a magnetic field of sufficient strength and quality to permit coupling with hearing aids that contain telecoils; and (2) provide an adequate range of volume. A telecoil is a small, tightly-wrapped piece of wire that, when activated, picks up the voice signal from the electromagnetic field generated by compatible telephones. Users of telecoil-equipped hearing aids are able to communicate effectively over the telephone without feedback and without the amplification of unwanted background noise.
A telephone that is hearing aid compatible often has a dedicated internal component, such as an HAC voice coil, that allows the use of telephone-compatible hearing aids. This dedicated HAC coil may be in addition to a receiver coil already present in the cellular phone. Yet, the inclusion of such an HAC coil in an already crowded space to meet the bandpass and other requirements of the MAC standard can pose significant challenges for cellular phone manufactures. As such, new techniques may be desirable to provide compliance with applicable standards, such as HAC standards (e.g., ANSI C63.19), without requiring larger form factors on hand held devices that are undesirable to users.
One exemplary HAC compatible mobile phone system is set forth in U.S. Patent Pub. No. 2006/0126873 to Lee. This reference discloses an apparatus for generating a magnetic field in a portable wireless terminal for a hearing impaired person. In the apparatus, an amplifier amplifies a voice-band electric signal received from a CODEC to a predetermined level, and a coil converts the amplified electric signal into a corresponding magnetic signal. The coil is configured to generate the magnetic signal sufficiently enough to allow a hearing impaired user wearing a hearing aid to make and receive calls with the portable wireless terminal.
Despite the existence of such systems, it may be desirable to provide further functionality and space saving features in mobile wireless communications devices that are hearing aid compatible.